DTC P0401: EGR Abnormal (EGR Amount Too Small): Notes

1. -

DTC detecting condition:

Detected when two consecutive driving cycles with fault occur.

Trouble symptom:

Infrequent knocking (P0401)
Improper idling (P0402)
Movement performance problem (P0402)

NOTE: After the faulty parts are repaired or replaced, perform the final check in Basic Diagnostic Procedure. Ref. to ENGINE (DIAGNOSTICS) (H4DO)>BASIC DIAGNOSTIC PROCEDURE>PROCEDURE .

CHECK DTC .
1. Turn the ignition switch to ON.
2. Using the Subaru Select Monitor or a general scan tool, read the DTC of [Engine].
  Ref. to COMMON (DIAG)>DIAGNOSTIC TROUBLE CODE (DTC) .
Are DTCs other than P0401 and P0402 displayed? (Current malfunction)

Yes : Check the appropriate DTC using the "Diagnostic Trouble Code (DTC)". Ref. to ENGINE (DIAGNOSTICS) (H4DO)>DIAGNOSTIC TROUBLE CODE (DTC) .

No :
- DTC P0401 displayed: Go to 2 .
- DTC P0402 displayed: Go to 3 .
CHECK DTC P0401 .
1. Turn the ignition switch to OFF.
2. Check for clogging in the pipes consisting of the EGR system.
  NOTE:
  Check the following items.
  - Throttle valve
  - EGR cooler
  - EGR control valve
  - EGR pipe
  - EGR pipe adapter
Is the check result OK?

Yes : Go to 4 .

No : Clean and replace the faulty parts.
CHECK DTC P0402 .
1. Turn the ignition switch to OFF.
2. Check for leakage in the pipes consisting of the EGR system.
  NOTE:
  Check the following items.
  - Looseness of each flange connection
  - Improper installation of throttle body
  - Improper installation of manifold absolute pressure sensor
  - Foreign matter attached to EGR valve
Is the check result OK?

Yes : Go to 4 .

No : Clean and replace the faulty parts.
CHECK FOR REPRODUCTION OF FAILURE .
Perform the corresponding inspection mode. Ref. to ENGINE (DIAGNOSTICS) (H4DO)>INSPECTION MODE .

Does the malfunction indicator light illuminate?

Yes : Replace the EGR control valve and manifold absolute pressure sensor. Ref. to EMISSION CONTROL (AUX. EMISSION CONTROL DEVICES) (H4DO)>EGR CONTROL VALVE . Ref. to FUEL INJECTION (FUEL SYSTEMS) (H4DO)>MANIFOLD ABSOLUTE PRESSURE SENSOR .

No : End.